From mboxrd@z Thu Jan 1 00:00:00 1970 From: olekstysh@gmail.com (Oleksandr Tyshchenko) Date: Mon, 27 Feb 2017 14:30:25 +0200 Subject: [PATCH v1 1/2] iommu/io-pgtable-arm: Check for leaf entry before dereferencing it In-Reply-To: <1488198626-1884-1-git-send-email-olekstysh@gmail.com> References: <1488198626-1884-1-git-send-email-olekstysh@gmail.com> Message-ID: <1488198626-1884-2-git-send-email-olekstysh@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Oleksandr Tyshchenko Do a check for already installed leaf entry at the current level before dereferencing it in order to avoid walking the page table down with wrong pointer to the next level. Signed-off-by: Oleksandr Tyshchenko CC: Will Deacon CC: Robin Murphy --- drivers/iommu/io-pgtable-arm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index feacc54..f9bc6eb 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -335,8 +335,12 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable *data, unsigned long iova, if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS) pte |= ARM_LPAE_PTE_NSTABLE; __arm_lpae_set_pte(ptep, pte, cfg); - } else { + } else if (!iopte_leaf(pte, lvl)) { cptep = iopte_deref(pte, data); + } else { + /* We require an unmap first */ + WARN_ON(!selftest_running); + return -EEXIST; } /* Rinse, repeat */ -- 2.7.4